Jason Bourne, by all accounts, was a cold-blooded and highly-trained -- but by all accounts fully human -- killer who awoke one day in the body of a disillusioned amnesiac; Aaron Cross is a gregarious charmer who only incidentally happens to kill people for a living, and with abilities granted to him by daily ingestion of little blue and red pills. That writer-director Tony Gilroy abandons the core identity (no pun intended) of the protagonist of the series -- a soulless, murderous automaton reconnecting with his humanity -- is dispiriting enough. But Gilroy further betrays the complexity of Damon's characterization of this world of black-ops killers by putting Cross only in defensive situations, and with one exception not showing anything from his history before he's disowned by his superiors.
But the larger problem is that the "man on the run" scenario that Gilroy throws Cross into feels hackneyed and familiar, no matter how desperately he tries first to contextualize it in the events of the first three films, and then attempt to bury its exhausted clichés with unnecessary, overwrought "complications." Although the groundwork for a rabbit-hole of shadowy government organizations was laid out in the first three films, the introduction of a new program -- "Outcome" -- instantly becomes comical, not the least of which because it seems to allow the filmmakers to have it both ways: to enjoy a tenuous link to "Legacy"'s predecessors, and introduce an "original" umbrella group whose members can operate independent of the characters we've previously seen.
Either way, it certainly doesn’t help that the first hour of the film is one long montage that cuts back and forth between Cross’ adventures before he's disavowed and flashbacks to what is "currently" happening with Treadstone and Blackbriar. Are we supposed to connect the two in some meaningful way, or simply be reminded of the government's untrustworthiness and then move forward with Cross's travails?
What's more infuriating is that this isn't deliberate mystery; Gilroy isn’t actively trying to lead the audience only to let them catch up later. He's really attempting to explain the absurd tangential connection "Legacy" has to the previous "Bourne" films, so that when the "real" plot takes over, audiences can simply take the ride and follow along.
Meanwhile, the crosscutting feels like a desperate victory lap for the filmmaker’s past accomplishments; notwithstanding the fact that Gilroy seems more interested in what’s going on behind closed doors with Byer than on the run with Cross, he's not merely drafting a blueprint for the mythology but reminding audiences how awesomely he once explored it. (This admittedly feels less deliberate than incidental -- the failures of this film only highlight the strengths of the others.)
As much as Rachel Weisz has matured into an incredibly capable and versatile actress, she takes a great leap backward as the doctor whom Cross protects, recalling her work as the bookish characters she played in the "Mummy" films and the Keanu Reeves thriller "Chain Reaction." While she convincingly plays a traumatized biologist, she exists for no other discernible purpose than to allow Renner to play Cross more sensitively, which subsequently gives his character no emotional journey, unless "oh man, people I used to work for are trying to kill me…that sucks" counts.